KR102308001B1 - On-site dissimilar metal welding technology for improved wear resistance and high manganese steel - Google Patents

Abstract

The present invention relates to a welding composition for joining a high manganese steel base metal to a low carbon steel base metal, as well as a system and method therefor. The composition comprises in the range of about 0.1% to about 0.4% by weight carbon; manganese in the range of about 15% to about 25% by weight; from about 2.0 weight percent to about 8.0 weight percent chromium; molybdenum in an amount up to about 2.0% by weight; nickel in an amount up to about 10% by weight; silicon in an amount up to about 0.7% by weight; sulfur in an amount of about 100 ppm or less; phosphorus in an amount of about 200 ppm or less; and the remainder comprising iron. In one embodiment, the composition has an austenitic microstructure.

Description

On-site dissimilar metal welding technology for improved wear resistance and high manganese steel

The present invention relates to the field of welding metals. More particularly, the present invention provides materials and methods for making weld metal required to join low carbon steel components to high manganese (Mn) components with improved wear resistance.

Cross-referencing of related applications

This application claims priority to U.S. Provisional Application No. 62/330,405, filed May 2, 2016, which is incorporated herein by reference in its entirety.

Piping systems in mining operations (including oil sand mining) transport a mixture of solid rock and sand particles in liquid or slurry to a processing plant and transport debris to a mining or storage area. used to return Current slurry hydro-transport pipes are typically made of low carbon pipeline grade steel (eg, API Spec 5L X65 or X70 grade steel). These pipes cause wall loss due to severe abrasive/erosive wear and corrosion and frequent repairs and replacements. Therefore, these piping systems are often a source of significant operating costs for mining projects. There are significant economic incentives to develop pipe materials with improved erosion/wear/corrosion resistance.

There also exists a need for enhanced wear-resistant steels in the oil sands mining industry. These oil sand deposits have been commercially recovered since the 1960s, and recovery rates have increased in recent years. Bitumen ore is typically a surface mining technique for shallow sediments (e.g. less than 100 m deep) or in-situ heat extraction for deep sediments located deeper underground (e.g. depths greater than about 100 m). (eg, including injection of steam, chemical solvents and/or mixtures thereof). Many types of heavy equipment and pipelines are utilized for surface mining of shallow oil sands. First, oil sands are typically excavated using a shovel that transports the mined material to a truck/vehicle. Vehicles move the oil sand ore to an ore preparation facility, where the mined ore is typically crushed and mixed with hot water. The oil sand slurry is typically pumped via a hydro-transport pipeline to a primary separation cell (PSC), where the oil bitumen is typically separated from sand and water. After the bitumen is separated, the remaining sand and water slurry is transported through a tailing pipeline to a tailing pond where the sand is settled. Hydro-transportation of large amounts of slurry mixture causes significant metal losses in conventional metal pipelines and the like, resulting in short replacement cycles and significant operating costs.

Thus, oil sand mining and ore manufacturing processes require a variety of stress and/or impact wear across multiple equipment/work areas (eg shovel teeth, hoppers, mills, conveyors, vibrating screens, slurry pumps, pipelines, etc.). entails problems Some of the problems encountered with equipment, pipelines (e.g. hydro-transport pipelines), pumps and/or PSCs, for example in downstream slurry transport and extraction processes, include erosion of equipment/materials, erosion/corrosion, corrosion, stress, abrasion and/or abrasion, and the like. These equipment/material erosion/corrosion problems, etc. result in significant repair, replacement and/or maintenance costs as well as production losses.

As mentioned, current piping structures for slurry hydro-transport are typically made of low carbon pipeline grade steel (eg API Spec 5L X70). In general, rapid movement of solids in a slurry flow can cause significant metal loss from the pipe (eg, metal loss in the inner pipe wall). Aqueous and aerated slurry flows also accelerate pipe erosion, typically by creating a corrosive environment. Moreover, particulate matter in the slurry (under the influence of gravity) causes damage, especially along the inner lower half of the pipe. For example, in oil sand mining operations, hydro-transport and tailing pipelines carrying sand and water slurries will experience severe erosion-corrosion damage during operation, whereas the bottom portion of the pipeline (e.g., the 6 o'clock position) will typically It experiences the most severe erosive wear.

To extend the operational life of the pipeline, some mining operators have used the practice of periodically rotating the pipeline. For example, pipelines are rotated by about 90° from time to time (eg, after about 3000 hours of operation). After about 3 revolutions (eg, after about 12000 hours of operation), the pipeline is typically completely replaced. A variety of materials have been evaluated and used by oil sand mining operators, such as martensitic stainless steels, hard-facing materials (eg WC-based, chromium-carbide-based) and polymer lining materials (eg polyurethane). . However, these materials typically have abrasion/erosion performance (eg polymer liners), high material/manufacturing costs (eg WC-based hard metals, chromium-carbide-based hard metal overlay materials), or limited usable thicknesses (eg : Only niche applications were confirmed with a double metal multilayer hardened steel material). However, pipe erosion and the like remain a serious problem, and alternative pipe structures and/or materials are needed to provide more efficient/economical operation/solutions.

Improved steel compositions with improved erosion/wear/corrosion performance have recently been developed to reduce operating costs in mining operations. In particular, improved high Mn steels with improved wear/erosion/corrosion resistance have been developed in oil sand mining applications including slurry pipes. For successful implementation, high Mn steel slurry pipe sections must be joined together in situ to create a high Mn steel slurry pipeline. Slurry pipelines are built using several types of joining methods, including girth butt welds, flanges, and mechanical couplings. Many of the flange systems and mechanical coupling systems require a metallic ring (often low carbon steel) to be joined to the outside of the pipe section at the pipe end. Welds used to join high Mn steel slurry pipes to low carbon steel rings and flanges must provide the required strength and toughness and must be applied during field construction without undue concern for "weldability" or ease of use.

Currently available welding techniques are not sufficient to join erosion-resistant high Mn steels to low-carbon steel components. High Mn steel weld metals developed so far for joining together sections of erosion-resistant high Mn steel have chemicals with great incompatibility with low carbon steels. Conventional high Mn steel consumables used to weld cast hardfield steels (usually used in railway parts) can be used to convert recently developed erosion-resistant high Mn steels to carbon steel for erosion/corrosion applications, such as oil sand applications. It does not provide sufficient weld metal strength to be used to join. High Mn steel welding consumables used in hard-faced applications cannot consistently provide the weld metal toughness levels required for these dissimilar metal welding applications.

US Patent Application Publication No. 2013/0174941 describes a high Mn steel developed for cryogenic applications such as storage vessels for liquefied natural gas (LNG). Weld metals were developed as cryogenic high Mn steels such as those described in JK Choi, et al, "High Manganese Austenitic Steel for Cryogenic Applications", Proceedings of the 22 ^{nd International ISOPE Conference, Rhodes, Greece 2012.} These cryogenic high Mn steel weld metals provide sufficient toughness at very low temperatures up to -200°C, but with high levels of erosion, erosion/corrosion, corrosion, stress, wear and/or abrasion such as conditions found in oil sand applications. does not provide adequate weld metal strength for joining erosion-resistant high Mn steels to low carbon steel components in applications involving

Thus, simultaneously producing adequate strength and adequate toughness during in-situ construction of high Mn steel pipelines, and in-situ bonding of other low carbon steel components to erosion-resistant high Mn steel components, without undue concern for weldability or ease of use. There is a need for a welding technique that can be used to build high Mn steel slurry pipelines for oil sand mining projects.

In certain aspects, the present invention provides, for example, bonding a low carbon steel component to an erosion resistant high Mn steel component (eg, a high Mn steel slurry pipe or other oil sand component) (eg, a high Mn steel Weld metals and methods of use that achieve strength and toughness suitable for bonding to Mn steel are provided. The present invention provides control of the weld metal chemistry, welding process, and welding practice that produces weld microstructure and mechanical properties suitable for the application.

In certain embodiments, the weld metal comprises from about 0.1 wt% to about 0.4 wt% carbon, from about 15 wt% to about 25 wt% manganese, from about 2 wt% to about 8 wt% chromium, about 2.0 wt% % molybdenum in an amount of about 3 wt% to about 10.0 wt% nickel, silicon in an amount of about 1.0 wt% or less, sulfur in an amount of about 200 ppm or less, and phosphorus in an amount of about 200 ppm or less, the balance being Fe (e.g. : about 70%). In other embodiments, another element that may be added to enhance weld metal properties (such as strength or toughness) is up to about 0.7 weight titanium.

In certain embodiments, the weld metal comprises one or more of: about 0.1 to 0.3 weight percent carbon; about 18.0 to 22.0 weight percent manganese; about 3.5 to 6.5 weight percent chromium; less than about 1.5 weight percent molybdenum; about 5.5 to 8.5 weight percent nickel; about 0.4 to 0.8 weight percent silicon; less than about 150 ppm sulfur; and up to about 0.7 weight percent titanium (eg, about 0.15 to 0.45 weight percent titanium).

In a further embodiment, the weld metal comprises from about 0.15 to about 0.45 weight percent titanium.

In another embodiment, the weld metal microstructure has an austenitic phase. In certain embodiments, the austenite phase can be converted to hard α′-martenzite and undergoes microtwinning upon transformation.

In another aspect, disclosed herein is a system for applying weld metal using welding equipment and parameters capable of controlling weld arc stability and weld pool flow properties, such as viscosity and bead shape to provide acceptable weldability. provides In certain embodiments, a system for providing welding for joining high Mn steel and low carbon steel includes a gas metal arc welding power source and a consumable wire electrode that performs gas metal arc welding. In certain embodiments, the consumable wire electrode comprises from about 0.1 wt% to about 0.4 wt% carbon, from about 15 wt% to about 25 wt% manganese, from about 2 wt% to about 8 wt% chromium, about 2 wt% % molybdenum in an amount of about 3% to about 10% by weight nickel, silicon in an amount of about 1.0% by weight or less, sulfur in an amount of about 150ppm or less, phosphorus in an amount of about 200ppm or less, and iron in an amount of about 200ppm or less. . A gas metal arc welding power source generates a welding heat input of less than about 2.5 kJ/mm.

In certain embodiments, the consumable wire electrode comprises about 0.1 to 0.3 weight percent carbon; about 18.0 to 22.0 weight percent manganese; about 3.5 to 6.5 weight percent chromium; less than about 1.5 weight percent molybdenum; about 5.5 to 8.5 weight percent nickel; about 0.4 to 0.8 weight percent silicon; less than about 150 ppm sulfur; and about 0.15 to 0.45 weight percent titanium.

In other embodiments, the welding heat input ranges from about 0.6 kJ/mm to about 1.0 kJ/mm.

In a further aspect, the present specification provides a method for applying a weld metal as described herein. In certain embodiments, the method comprises applying the weld metal described herein with welding equipment and parameters that allow control of weld pool flow properties, such as viscosity and bead shape, to provide acceptable weldability. . Weld metal chemistries, weld joint geometries, and weld inputs reduce susceptibility to solidification cracking and prevent significant degradation of weld metal and heat affected zone (HAZ) toughness in erosion resistant high Mn steel base metals and low carbon steel base metals controlled to do In a preferred embodiment, the weld metal of the present invention has a microstructure comprising austenitic grains.

In yet another aspect, provided herein is a method of creating a weld deposit for joining erosion resistant high Mn steel and low carbon steel. The method comprises: providing a high Mn steel base and a low carbon steel base to be welded, and a weld filler metal; and melting and cooling the weld filler material to form a weld deposit. In certain embodiments, the weld filler metal comprises from about 0.1 wt% to about 0.4 wt% carbon, from about 15 wt% to about 25 wt% manganese, from about 2 wt% to about 8 wt% chromium, about 2 wt% % molybdenum in an amount up to about 10 weight percent, nickel in an amount up to about 10 weight percent, silicon in an amount up to about 1.0 weight percent, sulfur in an amount up to about 100 ppm, phosphorus in an amount up to about 200 ppm, and iron.

In certain embodiments, said melting comprises applying a welding heat input to the weld filler metal of about 2.5 kJ/mm or less.

In certain embodiments, the base includes a portion to be welded, wherein the portion has an inclination greater than about 25°.

In other embodiments, the weld deposit has a yield strength in the welded state that is greater than the yield strength of the low carbon steel base or greater than the minimum required yield strength.

In certain embodiments, the weld deposit has at least one of a yield strength greater than about 70 ksi in the welded state, an ultimate tensile strength greater than 70 ksi in the welded state, and a welded state CVN greater than about 27 J at -29°C. has

In a further embodiment, the heat affected zone of the base metal has a post-weld CVN greater than about 27 J at -29°C.

In any aspect or embodiment described herein, the base metal or base steel is an erosion/corrosion resistant high Mn steel.

In any aspect or embodiment described herein, the method further comprises limiting the carbon content of the weld metal to an amount less than the carbon amount of the heat affected zone of the high Mn steel base metal.

The general scope of usefulness described above is given by way of example only and is not intended to limit the scope of the invention and the appended claims. Additional objects and advantages associated with the compositions, methods and processes of the present invention will be understood by those skilled in the art in light of the claims, detailed description and examples herein. For example, the various aspects and embodiments of the invention may be utilized in numerous combinations, all of which are expressly contemplated herein. These additional advantages, objects and embodiments are expressly included within the scope of the present invention. Publications and other documents used herein to set forth the background of the invention and particularly to provide additional details regarding its practice are incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several embodiments of the invention and, together with the description, serve to explain the principles of the invention. The drawings are for illustrative purposes only and should not be construed as limiting the present invention.
1A, 1B and 1C are heterogeneous weld macros for high Mn steel to carbon steel according to one embodiment.
2 is a schematic diagram illustrating a Victaulic ring to HMS pipe weld and weld bead sequence.
3 is a weld cross-section macro showing a weld joining a carbon steel bictolic ring to an erosion resistant high Mn steel pipe.

In the following detailed description, certain embodiments of the present disclosure are described in connection with preferred embodiments. However, when the following description is specific to a particular embodiment or to a particular use of the present disclosure, it is for illustrative purposes only and provides a description of exemplary embodiments only. This disclosure is not limited to the specific embodiments set forth below, but rather embraces all alternatives, modifications and equivalents falling within the spirit and scope of the appended claims.

Compared with typical carbon-manganese steel welding, due to the concentration of carbon, nickel and manganese in the high Mn steel weld metal, there is a problem that the high Mn steel weld metal is difficult to apply with conventional welding techniques. High Mn steel weld metal is substantially more viscous when melted compared to conventional low carbon steel weld metal. The increased viscosity of the molten high Mn steel weld metal can lead to lack of fusion defects in the weld toe located between the weld edge and the base metal. In addition, the toughness of the high Mn steel base metal is sensitive to thermal cycling due to welding. Consequently, if the heat input during welding is too high, the high Mn steel base metal HAZ can result in unacceptable levels of toughness. In addition, the weld metal solidifies as primary austenite. Therefore, if the weld metal composition and weld bead profile are not properly controlled, the weld tends to cause solidification cracking.

The system and the surprising and unexpected discovery that the dissimilar welded high Mn steel (DMW-HMS) of the present invention can be applied in the field of joining high Mn steel components with low carbon steel components having significant strength and toughness and Methods are described herein.

Various aspects and embodiments are exemplified with respect to high manganese steel components used to make oil sands. However, embodiments of the present invention are obviously more broadly applicable to any welding of erosion/abrasion resistant high manganese steel components to low carbon steel components where a weldment with adequate weldability, strength and toughness is desired. . Other such applications include, for example, bonding erosion resistant high Mn steel plates to structural low carbon steel or low carbon steel fixtures. Various terms are defined in the following specification.

Where a range of values is provided, it is understood that each intervening value between the upper and lower limits of that range and any other specified or intervening value within the stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included within the smaller ranges, and are included within the invention, subject to any specifically excluded limits within the stated ranges. Where the stated range includes one or both of the limits, ranges excluding both included limits are also included in the invention.

The following terms are used to describe the present invention. Where a term is not specifically defined herein, the term is given its art-recognized meaning by one of ordinary skill in the art applying the term in connection with its use in the description of the present invention.

All numerical values within the specification and claims are modified by “about” or “approximately” the indicated values and are subject to experimental errors and variations expected by those skilled in the art.

As used herein and in the appended claims, the terms "a" and "an" refer to one or more (ie, at least one) of the subject matter, unless expressly stated otherwise herein. By way of example, “an element” means one element or more than one element.

As used herein and in the claims, the phrase “and/or” refers to “either or both” of the elements so joined, i.e., in some cases present in combination and in other cases separately present. should be understood to mean Multiple elements listed with "and/or" should be construed in the same way, ie, "one or more" of the elements combined. Other elements may optionally be present other than those specifically identified by the phrase "and/or", whether or not related to the specifically identified element. Thus, as a non-limiting example, when used in conjunction with an open terminating language such as "comprising," reference to "A and/or B" is, in one embodiment, only A (an element other than B). optionally included); in other embodiments only B (optionally including elements other than A); In another embodiment, both A and B (optionally including other elements); Others may be mentioned.

As used herein and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, "or" or "and/or" should be construed as inclusive, i.e., the number or list of elements and, optionally, one or more of the non-listed additional items (also one Including excess). Only terms explicitly indicated to the contrary, such as "only one" or "exactly one," or, when used in the claims, the term "consisting of" means the inclusion of exactly one element in the list or number of elements. something to do. In general, the term "or," as used herein, when preceded by an exclusive term such as "either", "one of", "only one of that is, "either one or the other (but not both)").

In the claims and in the specification above, all transitional phrases such as "comprising", "including", "containing", "having", "containing", "comprising", "having", "consisting of", etc. is to be understood as meaning that it is open-ended, including but not limited to. Only transitional phrases such as "consisting of" and "consisting essentially of" will be closed or semi-closed transitional phrases, respectively, as disclosed in the 10 U.S. Patent Office Patent Examination Procedure Manual, Section 2111.03.

As used herein and in the claims, the phrase “one or more” in reference to a list of one or more elements means that the phrase "one or more" is selected from any one or more of the elements in the list of elements, provided that each and It is not necessary to include one or more of all elements and does not exclude any combination of elements in a list of elements) should be understood to mean one or more elements. This definition also allows for elements other than the specifically identified element to be arbitrarily present within the list of elements in which the phrase "one or more" is referenced, whether or not related to the specifically identified element. Thus, by way of non-limiting example, “at least one of A and B” (or equivalently, “at least one of A or B,” or equivalently, “at least one of A and/or B”) is one one or more (optionally including more than one) A (and optionally including elements other than B) without B; one or more (optionally including more than one) B (and optionally including elements other than A) without A in other embodiments; in another embodiment, one or more (optionally including more than one) A, and one or more (optionally including more than one) B, (and optionally including other elements); refer to, etc.

Unless expressly indicated to the contrary, in any method claimed herein that includes one or more steps or acts, the order of the method steps or acts need not be limited to the order in which the method steps or acts are recited. none.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the present invention is for the purpose of describing particular embodiments only, and is not intended to limit the present invention.

Justice:

Ductility: can mean, but is not limited to, a measure of the ability of a material to undergo significant plastic deformation before failure. This can be expressed as elongation (% EL) or area reduction (% AR).

Corrosion Resistance (Corrosion Resistance): Can mean, but is not limited to, the inherent resistance of a material to degradation caused by exposure to reactive or corrosive environments.

Toughness: can mean, but is not limited to, resistance to crack initiation and propagation.

Yield strength : can mean, but is not limited to, the ability of a material to withstand a load without deformation.

Tensile strength: When the failure mechanism is not linear elastic failure, it may mean, but is not limited to, the strength corresponding to the maximum load-carrying capacity of the material in units of stress.

Cooling rate: can mean, but is not limited to, the cooling rate of a material piece measured generally at or substantially at the center of the material piece.

Heat-affected-zone (HAZ): may mean, but is not limited to, a base metal adjacent to a weld fusion line that is not melted during a welding operation but is affected by the heat of the weld.

Weldment: may mean, but is not limited to, an assembly of component parts joined by welding.

Weld bead penetration profile : It may mean, but is not limited to, the shape of the weld bead near the bottom (root) of the weld bead when viewed in a cross-section.

Weldability : Can mean, but is not limited to, the ability to weld certain metals or alloys. Sometimes weldability refers to the susceptibility of hydrogen induced cracking during welding, but weldability in the context of this specification refers to the ease of welding that does not produce defects such as lack of fusion, lack of penetration or undercuts. There are several factors that contribute to poor weldability, including high surface tension molten weld pools and irregular or unstable welding arcs. These factors cause symptoms observed in welders, including poor wettability of the weld pool of adjacent base metals, sharp (or small) re-entry angles in the weld toe, and undesirable weld spatter. Achieving good weldability includes good weld pool fluidity, arc stability (“smooth” arc), good wettability of the weld pool at the junction with the base metal, and good bead penetration geometry (all aimed at reducing weld defects). attribute groups, including

Gas Metal Arc Welding (GMAW) : A welding process using a torch in which a filler wire acts as an electrode, is fed automatically through a contact tip, and is consumed in the welding process. The contact tip is typically surrounded by a gas cup that directs shielding gas into the area of the welding arc. Common shielding gases are argon, carbon dioxide, helium and oxygen. Torch movement can be provided by a machine (automatic or mechanical) or by a human (semi-automatic). The process designation GMAW is the standard designation of the American Welding Association.

Pulsed Gas Metal Arc Welding (PGMAW) : A variant of the GMAW process that uses a power source that provides current pulsing capability. It is also referred to as an advanced current waveform power supply. The American Welding Association refers to PGMAW as GMAW-P.

GMAW-Based Processes : Many associated processes similar to GMAW, such as PGMAW, Metal Core Arc Welding (MCAW) and Flux Core Arc Welding (FCAW). The main difference from MCAW is that a cored wire is used and metal powder is present in the core. The FCAW process also uses a cored wire and the core is typically composed of a flux powder. FCAW can be used with or without shielding gas.

Austenite : may mean, but is not limited to, a metallurgical phase of steel having a surface-centered cubic (FCC) atomic crystal structure.

martensite : may refer to a metallurgical phase in a steel that can be formed (but is not limited to) by a diffusionless phase transformation in which the parent phase (typically austenite) and the product phase have a specific orientation relationship, but , but not limited thereto.

ε (epsilon)-martensite : may refer to a specific type of martensite having a close packed hexagonal atomic crystal structure when the austenite phase is cooled or deformed, but is not limited thereto. ε-Martensite typically forms on the dense (111) plane of the austenite phase and resembles strain twins or morphologically stacked defect clusters.

α' (alpha prime)-martensite : may refer to a specific type of martensite having a body-centered cubic (BCC) or body-centered tetragonal (BCT) atomic crystal structure, which is formed upon cooling or deformation of the austenite phase, but is limited thereto not to be; α'-martensite is typically formed as platelets.

Carbide : It may mean a compound of iron/metal and carbon, but is not limited thereto.

Weld metal composition :

In one aspect, the present disclosure provides an austenitic weld metal that is applied using a state-of-the-art gas metal arc welding (GMAW) process. It is useful for welding erosion-resistant high Mn steel components to low carbon steel components, capable of simultaneously achieving adequate strength, adequate low temperature toughness in both weld metal and base metal heat affected zones, and low defect rate welds. create a microstructure. Embodiments of the present invention provide a class of attributes including good weld pool fluidity, arc stability (“smooth” arc), good wettability of the weld pool at the junction with the base metal, and good bead penetration geometry, all of which are susceptible to weld defects. good weldability is obtained.

The DMW-HMS weld metal chemistry can be used together with the base metal HMS chemistry and the base metal HMS chemistry to calculate the required consumable welding wire composition. In a similar manner, consumable welding wire chemistries, base metal HMS chemistries, and base metal low carbon steel chemistries can be used to calculate the DMW-HMS weld metal chemistry. DMW-HMS chemistries can be applied to a variety of HMS and low carbon steel base metals with the knowledge of the welding process to control changes in welding wire chemistry and penetration and base metal dilution. As is known to those skilled in the art of welding engineering, dilution calculations can be used to determine one of four chemicals when three chemicals are known or specified. For welded HMS-carbon steel components (eg low carbon steel rings to HMS slurry pipes), four metals are involved: HMS base metal, low carbon steel base metal, weld metal and filler wire. For the applications of MCAW welding described herein, the dilution is typically between 5% and 20% in the majority of weld passes. Dilution calculations are known in the art and are described in many welding engineering textbooks, including Welding Metallurgy, Volume 2, Third Edition, by George E. Linnert that was published by The American Welding Society.

The weld metal of the present invention produces suitable mechanical properties in dissimilar metal welding, such as joining low carbon steel rings and flanges to erosion resistant high Mn steel (HMS), such as HMS slurry pipe. These new welds are suitable for slurry pipelines, and these welds can be applied during field construction with acceptable weldability and defect rates. The weld metal desired for a particular application is designed with a selection of weld metal chemistries and welding methods, and can be applied to rugged field pipeline construction conditions to produce appropriate weld microstructure and mechanical properties.

In one embodiment, the weld metal comprises from about 0.1 wt% to about 0.4 wt% carbon, from about 15 wt% to about 25 wt% manganese, from about 2 wt% to about 8 wt% chromium, about 2.0 wt% % molybdenum in an amount up to about 10.0 weight percent nickel, silicon in an amount up to about 1.0 weight percent sulfur, in an amount up to about 200 ppm sulfur, and phosphorus in an amount up to about 200 ppm, the balance being Fe. Unless otherwise specified, all percentages related to the composition of the weld metal are expressed in weight percent. The balance of the weld metal composition is iron, but the weld metal may include other unlisted components, such as impurities, for example.

Other elements may be added for other reasons described below. For example, titanium may be added in an amount of about 0.7% by weight or less.

In some embodiments, the weld metal comprises one or more of: about 0.1 to 0.3 weight percent carbon; about 18.0 to 22.0 weight percent manganese; about 3.5 to 6.5 weight percent chromium; less than about 1.5 weight percent molybdenum; about 5.5 to 8.5 weight percent nickel; about 0.4 to 0.8 weight percent silicon; less than about 150 ppm sulfur; and about 0.15 to 0.45 weight percent titanium.

The high Mn steel weld metal described in the present invention is designed to meet the minimum mechanical properties of the base metal low carbon steel and the base metal high Mn steel used in applications where two steels need to be joined by welding, such as slurry pipe applications. is required As such, the DMW-HMS weld metal microstructure can be suitably used with both erosion-resistant HMS base metal and low carbon steel microstructures. A suitable weld metal microstructure for this purpose consists of a metastable austenite phase with a face-centered cubic (fcc) structure at room temperature.

Upon deformation, the metastable austenitic phase can undergo many different phase transformations through strain-induced transformations. This transformation results in microtwins (fcc) of the austenite phase, in which the twins are aligned with the matrix, ε-martensite (hexagonal lattice) and α'-martensite (body-centered tetragonal lattice), depending on the specific strong chemistry and/or temperature. ) to be transformed into a structure.

These conversion products are important for creating the unique properties of high Mn steels. For example, the fine microstructure effectively segments primary austenite grains and acts as a major obstacle to dislocation motion. It effectively refines the grain and produces an excellent combination of high ultimate tensile strength and ductility.

The chemical properties of the base metal erosion-resistant high Mn steel have been specially tuned to produce conversion products that provide good erosion and wear performance. The base metal is prepared to contain a highly metastable austenite phase, which is often converted to hard α′-martensite upon transformation. Upon surface wear of these steels, the surface layer of the highly metastable austenite phase may be converted to α′-martensite. This friction-induced phase transition results in the formation of a thin hard surface layer of martensite on the interior of the tough, untransformed metastable austenite. This is the preferred combination for wear/erosion applications. In one embodiment, the high Mn steel base metal is provided as described in 2013EM118, PCT/US2014/020599 entitled "Enhanced Abrasion Resistant Steel and Method of Making Same".

The DMW-HMS weld metal of the present invention for joining low carbon steel and corrosion-resistant HMS is not exposed to erosive action. For example, DMW-HMS can be used to bond low carbon steel rings or flanges to the exterior of an erosion-resistant HMS slurry pipe, such that DMW-HMS is not exposed to the erosive action inside the pipe. Therefore, wear-induced surface transformation for improved erosion resistance required for erosion-resistant HMS base metal is not required for DMW-HMS weld metal. In one embodiment, the carbon level of the weld metal is controlled to a level significantly lower than the carbon level of the erosion resistant HMS base metal. Low carbon levels maintain a stable austenitic phase to meet strength and low temperature toughness requirements and are more compatible with low carbon steel base metals. Manganese is a major element in high Mn steel and is important for stabilizing the austenite structure during cooling and deformation. As such, in one embodiment, the manganese level in the weld metal is similar to the base metal.

In austenitic HMS, carbon acts as an effective austenite stabilizer and also strengthens the matrix by solid solution hardening. Reducing the carbon content of the DMW-HMS weld metal requires alloying the weld metal with some additional elements to produce the required strength properties.

Silicon addition provides some solid solution strengthening in addition to maintaining the α'-martensitic transformation. Silicon also improves weldability by improving the fluidity of the weld pool at all welding positions during welding. In one embodiment, the silicon content in the weld metal is increased beyond the base metal level due to weldability benefits, for example in the range of from about 0.7% to about 0.6% by weight. In certain embodiments, the silicon is present in an amount of about 0.4 to 0.7 by weight.

Chromium addition increases corrosion resistance and is important to ensure that the weld metal corrosion resistance is sufficient for the application. The addition of higher levels of chromium promotes ferrite phase formation during cooling and carbide formation during cooling and reheating. In some embodiments, the chromium content ranges from about 2.0% to about 8.0% by weight. In other embodiments, the chromium content in the weld metal is from about 2.0 wt% to about 8.0 wt%, from about 2.0 wt% to about 7.0 wt%, from about 2.0 wt% to about 6.0 wt%, from about 2.0 wt% to about 5.0 wt% , about 2.0 wt% to about 4.0 wt%, about 2.0 wt% to about 3.0 wt%, about 3.0 wt% to about 8.0 wt%, about 3.0 wt% to about 7.0 wt%, about 3.0 wt% to about 6.0 wt% , about 3.0 wt% to about 5.0 wt%, about 3.0 wt% to about 4.0 wt%, about 4.0 wt% to about 8.0 wt%, about 4.0 wt% to about 7.0 wt%, about 4.0 wt% to about 6.0 wt% , about 4.0 wt% to about 5.0 wt%, about 5.0 wt% to about 8.0 wt%, about 5.0 wt% to about 7.0 wt%, about 5.0 wt% to about 6.0 wt%, about 6.0 wt% to about 8.0 wt% , from about 6.0% to about 7.0% by weight, or from about 7.0% to about 8.0% by weight. In other embodiments, the chromium content is about 2.0 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt%, about 4.5 wt%, about 5.0 wt%, about 5.5 wt%, about 6.0 wt% weight percent, about 6.5 weight percent, about 7.0 weight percent, about 7.5 weight percent, or about 8.0 weight percent.

Molybdenum addition provides significant solid solution strengthening. The addition of molybdenum is important to achieve the required strength properties in DMW-HMS weld metal. The weld metal of the present invention may comprise molybdenum in an amount up to about 2.0 weight percent.

Nickel addition can provide additional austenite stability and improve weld metal toughness. However, adding higher levels of nickel may reduce strength. In some embodiments, the weld metal comprises nickel in an amount of up to about 10 weight percent. In certain embodiments, nickel is present in an amount of about 7%. In some embodiments, nickel is about 0-10% by weight, about 0-9% by weight, about 0-8% by weight, about 0-7% by weight, about 0-6% by weight, about 0-5% by weight, about 0-4 wt%, about 0-3 wt%, about 0-2 wt%, about 0-1 wt%, about 1-10 wt%, about 1-9 wt%, about 1-8 wt%, about 1 -7% by weight, about 1-6% by weight, about 1-5% by weight, about 1-4% by weight, about 1-3% by weight, about 1-2% by weight, about 2-10% by weight, about 2- 9 wt%, about 2-8 wt%, about 2-7 wt%, about 2-6 wt%, about 2-5 wt%, about 2-4 wt%, about 0-3 wt%, about 3-10 wt% wt%, about 3-9 wt%, about 3-8 wt%, about 3-7 wt%, about 3-6 wt%, about 3-5 wt%, about 3-4 wt%, about 4-10 wt% %, about 4-9 wt%, about 4-8 wt%, about 4-7 wt%, about 4-6 wt%, about 4-5 wt%, about 5-10 wt%, about 5-9 wt% , about 5-8 wt%, about 5-7 wt%, about 5-6 wt%, about 6-10 wt%, about 6-9 wt%, about 6-8 wt%, about 6-7 wt%, It is present in an amount of about 7-10% by weight, about 7-9% by weight, about 7-8% by weight, about 8-10% by weight, about 8-9% by weight, or about 9-10% by weight. In certain embodiments, the weldment is about 0.0 wt%, about 0.5 wt%, about 1.0 wt%, about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt% %, about 4.5 wt%, about 5.0 wt%, about 5.5 wt%, about 6.0 wt%, about 6.5 wt%, about 7.0 wt%, about 7.5 wt%, about 8.0 wt%, about 8.5 wt%, about 9.0 wt% %, about 9.5 weight percent, or about 10.0 weight percent nickel.

There are several additional minor element additives that can be added to the DMW-HMS weld metal. Small amounts of titanium (eg, up to about 0.7 wt % or about 0.15-0.45 wt %) may be added for grain refining and precipitation hardening purposes to strengthen the weld metal.

Sulfur and phosphorus are impurities and are not intentionally added. These elements are controlled by limiting their amounts in the welding consumables. The amount of sulfur and phosphorus should be controlled to avoid weld solidification cracking. For example, in one embodiment, sulfur and phosphorus are each present in a concentration of about 200 ppm or less.

In some embodiments, the weldment is about 15-25 wt%, about 15-23 wt%, about 15-21 wt%, about 15-19 wt%, about 15-17 wt%, about 17-25 wt%, about 17-23% by weight, about 17-21% by weight, about 17-19% by weight, about 19-25% by weight, about 19-23% by weight, about 19-21% by weight, about 21-25% by weight, about 21 -23 weight percent, or about 23-25 weight percent manganese.

Weld metallurgy/microstructure/mechanical properties :

The novel DMW-HMS weld metal can provide the strength and toughness needed to bond erosion-resistant HMS components (including slurry pipes) to low carbon steel components. The microstructure necessary to meet these property requirements is achieved through appropriate control of the weld metal chemistry and welding process parameters.

The DMW-HMS weld metal must achieve the minimum tensile strength properties required for the application (eg slurry pipe). For example, the weld metal tensile strength must be greater than the specified minimum ultimate tensile strength (SMUTS) (the lowest in any case) required by the component design for erosion-resistant HMS base materials or low carbon steel component base materials. . In some embodiments described herein, the SMUTS for low carbon steel components is lower than the SMUTS for erosion resistant HMS components. In one embodiment, the DMW-HMS weld metal of the present invention achieves all these requirements because it is a highly metastable austenitic phase, which is converted to hard α′-martensite and undergoes micro-twinning upon deformation. In addition, solid solution strengthening elements (eg, molybdenum) in the weld metal can provide additional reinforcement by perturbing the lattice dislocation motion. In one embodiment, the combination of these reinforcing mechanisms provides high strength and work hardening rates to achieve tensile strength requirements.

The DMW-HMS weld metal must achieve the minimum toughness properties required for the application (eg slurry pipe). Also, the base metal (HAZ) near the weld must achieve these minimum toughness properties. The most common assessment of toughness for an intended application is impact toughness as measured by performing a Charpy V-notch (CVP) test of several inverse regions of the weld metal and HAZ. The test value reported in units of energy (ie, joules, J) shall be greater than the minimum required CVN specified by the design code for the application. DMW-HMS welding meets the requirements of weld metal, erosion-resistant HMS base metal HAZ and low carbon steel HAZ. In one embodiment, weld metal toughness is achieved with a weld metal microstructure composed of an austenitic phase and a limited amount of carbide to provide a mode of ductile fracture. Erosion-resistant base metal HAZ toughness can be achieved by controlling the weld heat input to minimize carbide precipitation in the HAZ. High heat input can lead to excessive carbide precipitation at the erosion-resistant HMS HAZ grain boundaries and increase the hardness of the HAZ, resulting in inadequate CVN toughness values. In one embodiment, the low carbon steel HAZ toughness is achieved by controlling the heat input. Controlling the heat input during welding can avoid the formation of phases with high hardness and low toughness, such as martensite.

In certain embodiments, the weld metal of the present invention has a microstructure comprising austenitic grains.

In another embodiment, the weld metal has a yield strength in the as-welded state that is greater than the yield strength of the high manganese steel base and/or low carbon steel, or greater than the minimum required yield strength.

In one embodiment, the weld metal has a yield strength of greater than about 70 ksi in the welded state. In certain embodiments, the yield strength is greater than about 72.5 ksi, about 75 ksi, about 77.5 ksi, about 80 ksi, or about 82.5 ksi.

In some embodiments, the weld metal has an ultimate tensile strength greater than 70 ksi in the welded state. In certain embodiments, the ultimate tensile strength is greater than about 85 ksi, about 90 ksi, about 95 ksi, about 100 ksi, about 105 ksi, about 110 ksi, about 115 ksi, about 120 ksi, about 125 ksi, or about 130 ksi. Big.

In another embodiment, the weld metal has a welded state CVN energy of greater than about 27 J at -29°C. In certain embodiments, the weld deposit is, at -29°C, about 30 J, about 35 J, about 40 J, about 45 J, about 50 J, about 55 J, about 60 J, about 65 J, about 70 J , has a welded state CVN energy greater than about 75 J, or about 80 J.

In another embodiment, after application of the weld metal, the high Mn steel HAV has a welded state CVN energy of greater than about 27 J, at -29°C. In certain embodiments, the high Mn steel HAV is about 30 J, about 35 J, about 40 J, about 45 J, about 50 J, about 55 J, about 60 J, about 65 J, about 70 J at -29°C. , has a welded state CVN energy greater than about 75 J, or about 80 J.

In another embodiment, after application of the weld metal, the low carbon steel HAZ has a welded state CVN energy of greater than about 27 J at -29°C. In certain embodiments, the low carbon steel HAZ at -29°C is about 30 J, about 35 J, about 40 J, about 45 J, about 50 J, about 55 J, about 60 J, about 65 J, about 70 J , has a welded state CVN energy greater than about 75 J, or about 80 J.

Weldability :

The novel DMW-HMS weld metal can provide the weldability needed for joining erosion-resistant HMS to low carbon steels. This weldability is achieved through proper control of weld metal chemistry, welding process parameters, and weld joint design.

In one embodiment, the DMW-HMS weld metal solidifies as primary austenite. Primary austenitic structures can be susceptible to weld solidification cracking. Since any weld solidification cracking is unacceptable for the manufacture of oil sand components, including slurry pipelines, the DMW-HMS weld metal must provide adequate resistance to solidification cracking during welding using actual welding parameters. Proper control of weld metal chemistry can help prevent solidification cracking of DMW-HMS weld metal. Controlling the composition of the consumable wire can help ensure adequate levels of alloying elements and minimal levels of impurity elements such as sulfur and phosphorus. The dilution of the base metal must be controlled to ensure that the weld metal composition range is within the appropriate range. Base metal HMS has a much higher carbon content than DMW-HMS welding consumables, so it can have a greater dilution resulting in greater solidification cracking susceptibility. In one embodiment, the dilution level is controlled by limiting the maximum heat input. In other embodiments, the dilution level is controlled by a predetermined weld bead sequence. Solidification cracks also depend on the magnitude and location of weld residual stresses that occur during weld metal solidification. In a further embodiment, a specific weld bevel geometry is used to provide more favorable weld residual stress and improved resistance to solidification cracking in DMW-HMS weld metal. For example, in one embodiment, an open bevel with a larger included angle produces a weld bead with a smaller depth-to-width ratio. This may reduce solidification cracking susceptibility compared to narrow slopes with smaller included angles and larger thermally induced stresses. Thermally induced stress may also be controlled by ensuring proper fit up alignment of the dissimilar metal components. As such, HMS components and low carbon steel components must be properly controlled within specified dimensional tolerances.

Welding process parameters and welding application examples :

According to another embodiment of the present invention, a system for applying a weld metal of the present invention is provided. The system can use welding equipment and parameters to control weld arc stability and weld pool flow properties such as viscosity and bead shape to provide acceptable weldability. A system for providing welding for joining high Mn steel and low carbon steel includes a gas metal arc welding power source for performing gas metal arc welding and a consumable wire electrode. The consumable wire electrode comprises the aforementioned weld metal. For example, the wire electrode may comprise from about 0.1 wt% to about 0.4 wt% carbon, from about 15 wt% to about 25 wt% manganese, from about 2.0 wt% to about 8.0 wt% chromium, about 2.0 wt% molybdenum in an amount up to about 10 weight percent nickel, silicon in an amount up to about 0.70 weight percent sulfur, in an amount up to about 100 ppm sulfur, and phosphorus in an amount up to about 200 ppm, and the balance comprising iron. A gas metal arc welding power source generates a welding heat input of less than about 2.5 kJ/mm. In other embodiments, the welding heat input ranges from about 0.6 kJ/mm (about 15 kJ/inch) to about 1.0 kJ/mm (about 25 kJ/inch).

Application of sound DMW-HMS welding produced with practical productivity for building slurry pipelines can be achieved with recently developed welding techniques. Industry available GMAW welders enable excellent weldability for DMW-HMS welds. GMAW power manufacturers have included advanced pulsed waveform control using sophisticated solid-state electronics. This waveform control can improve and optimize weldability. This type of welding is typically also referred to as pulsed GMAW or PGMAW. These PGMAW devices have existed for many years, but only recently have their waveform control capabilities advanced sufficiently to enable the most favorable level of optimization for ER-HMS field deployments.

In one embodiment, the DMW-HMS weld is made with a GMAW welder. In certain embodiments, DMW-HMS welding is applied with pulsed GMAW (PGMAW). DMW-HMS consumable chemicals can be welded to multiple welding positions (1G-Plane, 2G-Horizontal, 3G-Vertical, 4G-Overhead, 5G-Pipe Horizontal) using, for example, a commercially available GMAW welder. . Welding consumables can be applied as stringer beads or weave beads. The parameters can be selected to ensure proper base metal bonding and fusion on both the HMS side of the weld and the low carbon steel side of the weld.

In certain embodiments, the low carbon steel rings are bonded to the exterior of the HMS slurry pipe during construction of the on-site slurry pipeline. In other embodiments, DMW-HMS welding is made using a GMAW-based process, such as PGMAW. Other processes may be used if specific chemistries and microstructures are achieved and weldability is satisfactory for the application. Some examples of power sources that can be used are the Fronius TransSynergic 3200, the Lincoln Power Wave 455 and the Miller PipePro 450.

Systems that apply DMW-HMS welding to join low carbon steel (e.g., low carbon steel rings) to HMS (e.g., the exterior of an erosion-resistant HMS slurry pipe) use cored wire consumables (metal cores or flux cores). Semi-automatic GMAW welding may be included. Welding may be performed with a current of about 100 to about 180 amps. The arc voltage may range from about 15V to about 30V. Wire feed rates may range from about 80 to about 500 ipm for a wire with a diameter of about 1.2 mm. In addition, welding may be performed with a weld shielding gas flow rate in the range of about 10 to about 50 cfh. In other embodiments, a filler wire having a diameter ranging from about 1.2 mm to about 1.6 mm may have a travel speed ranging from about 1 to about 18 ipm for the root, fill and cap passes. In some embodiments, the welding is performed with a heat input of less than about 2.5 kJ/mm (63.5 kJ/inch). In certain embodiments, the welding is performed with a heat input of less than about 1.97 kJ/mm (50 kJ/inch). The heat input may range from about 0.59 kJ/mm (about 15 kJ/inch) to about 1.02 kJ/mm (about 26 kJ/inch).

According to another embodiment of the present invention, a method for applying a weld metal of the present invention is provided. This method uses welding equipment and parameters that can control weld arc stability and weld pool flow properties, such as viscosity and bead shape, to provide acceptable weldability. In one embodiment, the weld metal chemistry, weld joint geometry, and weld input are controlled to ensure strength and toughness of the weld metal and to prevent significant degradation of heat affected zone (HAZ) toughness.

A method of making a weld weldment for joining high Mn steel and low carbon steel comprises: providing a high Mn steel base and a low carbon steel base to be welded, and a weld filler metal; and melting and cooling the weld filler material to form a weld deposit. The weld filler metal may include carbon in the range of about 0.1% to about 0.4% by weight, manganese in the range of about 15% to about 25% by weight, chromium in the range of about 2.0% to about 8.0% by weight, in an amount up to about 2.0% by weight. of molybdenum, nickel in an amount up to about 10 weight percent, silicon in an amount up to about 0.70 weight percent, sulfur up to about 100 ppm sulfur, phosphorus up to about 200 ppm, and iron in an amount of up to about 0.70 weight percent.

In certain embodiments, the melting comprises applying a welding heat input of about 2.5 kJ/mm or less to the weld filler metal/weld consumable wire composition.

In certain embodiments, the high Mn steel base and/or carbon steel base metal comprises a portion to be welded, wherein the portion(s) has a slope greater than about 25°.

One embodiment of the present invention includes a method of making a DMW-HMS weld for specific application requirements. The method includes determining the desired DMW-HMS weld metal chemistry within the effective range disclosed herein. In one embodiment, the method comprises determining a weld consumable wire chemistry given a base metal chemistry and a desired weld metal chemistry, which may include performing the previously discussed dilution calculations. In another embodiment, the method further comprises welding the base metal using the weld consumable wire. In certain embodiments, welding includes controlling arc stability and weld pool flow properties during welding to provide satisfactory weldability and weld fusion.

Example

Inspection of DMW-HMS Weld Metal: Lab scale testing of DMW-HMS weld metal was performed. A semi-automatic GMAW process was performed with the following parameters: a current of about 120 to 145 amps; arc voltage typically from about 20V to about 30V; a wire feed rate of about 220 to 250 ipm for a 1.2 mm diameter wire; a shielding gas flow rate of about 40 to about 50 cfh; travel speed of about 3 to about 8 ipm for root, fill and cap passes; Filler wire diameter of about 1.2 mm; and a heat input of about 18-50 kJ/inch. Table 1 shows the properties of test welds (eg, yield strength, tensile strength, etc.).

Table 1. Example weld metal chemistries and related properties for several test welds.

The ultimate tensile strength and CVN impact toughness at -29°C of weld metal are listed in Table 2, and immersion resistant HMS slurry pipe and low carbon steel ring with API X70 grade based strength requirements (ASME SA-516 grade 70 material) Welding requirements for joints between The DMW-HMS weld metal tensile strength must be greater than the specified ultra-small ultimate tensile strength (SMUTS) of the lower strength material, a low carbon steel ring. The SMUTS for the corrosion-resistant HMS material is 82.7 ksi, and the SMUTS for the low carbon steel is 70 ksi. As such, the DMW-HMS weld metal must be greater than 70 ksi (the lower of the two SMUTS values). Modifications to the DMW-HMS weld metal chemistry can be performed within the ranges disclosed herein to achieve the weld metal tensile properties required for low carbon steel joints in the potentially erosion resistant HMS range. Table 2 also lists the impact toughness (CVN) values achieved with the resulting DMW-HMS test welds and compared to the weld impact toughness requirements for slurry pipe applications.

Table 2. Weld metal mechanical properties for carbon steel-HMS test welds.

Qualification of field welding procedures . Table 3 shows the average test results of carbon steel-HMS welds produced as part of the testing of the welding procedure. The test weld results are reported together with the required values. The carbon steel-HMS welding procedure showed good impact toughness values as well as cross-weld tensile strength for weld metal, high Mn steel and low carbon steel.

Table 3. Weld metal properties of carbon steel-HMS welds.

The foregoing embodiments are capable of producing HMS for low carbon steel welds that meet all requirements for making and applying erosion resistant HMS slurry pipelines.

Proper control of the weld shielding gas composition is critical to the production of good carbon steel HMS welds with the required properties. The viscosity of the DMW-HMS weld metal is overcome by using _{CO 2 in the shielding gas.} The CO ₂ in the shielding gas serves to improve the bead geometry, including weld pool fluidity, arc stability, and penetration profile. All these properties are important to avoid welding defects during welding. However, the _{use of CO 2} may increase the oxygen potential and increase the oxygen content of the weld metal. Excessive oxide formation in the weld metal can degrade toughness. Therefore, _{the amount of CO 2 in} the shielding gas should be controlled between 10% and 30%. In a preferred embodiment, the DMW-HMS welding technique applies a shielding gas having a composition _{of 80 % Ar/20 % CO 2 .}

The weld bead profile of DMW-HMS welds must be properly controlled to minimize the risk of solidification cracking. Highly concave bead profiles should be avoided as they are prone to solidification cracking. The bead profile can be controlled by appropriately controlling the welding current, wire feed speed, and welding travel speed.

When using cored wire consumables to apply DMW-HMS welding, it is important to avoid typical welding problems that may be associated with cored wire welding processes such as metal MCAW and FCAW. These potential problems include excessive spatter and weld metal porosity. As mentioned above _{, the use of CO 2} in the shielding gas will reduce spatter. Weld metal porosity can be reduced or avoided through appropriate cleaning methods, such as drying and cleaning the weld joint and consumable wire, and removal of oil and other debris. Appropriate consumable storage practices (temperature and humidity) must be followed as cored wire consumables are more prone to collecting moisture during improper storage than solid wire consumables.

Welding process parameters can be controlled to produce a weld heat input that provides good DMS-HMS welds with suitable microstructure and properties for slurry pipe applications. Weld heat input must be high enough to enable consistent fusion with practical productivity for pipeline welding. However, it should be controlled to a maximum of less than about 2.5 kJ/mm to ensure a welding that meets the requirements. Welding parameters (current, voltage and travel speed) can be adjusted to ensure that the welding heat input values are not exceeded. Excessive heat input exceeding the maximum can lead to many potential problems including solidification cracking, reduced weld metal toughness, and reduced base metal HAZ toughness.

Weld heat input can be controlled below the maximum value to avoid creating large weld beads with high depth-to-width ratios that can cause solidification cracking. Such a high depth-to-width ratio may increase the likelihood of solidification cracking due to increased segregation of the weld metal and increased lateral strain in the weld joint.

In addition, welding heat input control is important to maintain the required toughness in HMS base metal HAZ and low carbon steel base metal HAZ. In the HMS base metal HAZ, it will be understood that if the heat input is too high, excessive carbide precipitation will occur at the grain boundaries of the HMS base metal HAZ. This can result in localized areas with reduced toughness. Controlled welding heat input below the maximum provides a heat cycle and cooling rate that reduces the amount of carbide deposits at the HAZ grain boundary. This improves fracture toughness and resistance to cracking. Therefore, proper heat input control is required to ensure the required toughness in both the DMW-HMS weld metal and the HMS base metal HAZ. Heat input control also reduces the formation of low toughness microstructures (eg martensite) in the low carbon steel base metal HAZ.

Proper application of the weld metal chemistries, welding processes and welding methods described above will produce suitable DMW-HMS welds with the microstructure and mechanical properties necessary to build HMS slurry pipelines. The novel DMW-HMS weld metal can be applied in 1G, 2G, 3G, 4G and 5G welding locations with practical productivity using modern pipeline welding equipment.

Specific embodiments :

According to one aspect, the present invention provides a welding composition for bonding a high manganese steel base metal to a low carbon steel base metal, the composition comprising in the range of 0.1 wt % to 0.4 wt % carbon; manganese in the range of 15% to 25% by weight; 2.0 wt% to 8.0 wt% chromium; molybdenum in an amount up to 2.0% by weight; nickel in an amount of up to 10% by weight; silicon in an amount up to 0.7% by weight; sulfur in amounts up to 100 ppm; phosphorus in amounts of 200 ppm or less; and the remainder comprising iron, wherein the weldment comprises an austenitic microstructure.

In any aspect or embodiment described herein, the welding composition further comprises titanium in an amount up to 0.7 weight percent.

In any aspect or embodiment described herein, 0.1 to 0.3 weight percent carbon; 18.0 to 22.0 weight percent manganese; chromium from 3.5 to 6.5% by weight; molybdenum in an amount of less than 1.5% by weight; 5.5 to 8.5 weight percent nickel; 0.4 to 0.8 weight percent silicon; sulfur is less than 150 ppm; A preferred range of titanium is 0.15 to 0.45% by weight.

In any aspect or embodiment described herein, the weld filler metal has an austenitic microstructure.

In any aspect or embodiment described herein, the austenitic microstructure is converted to hard α′-martensite and undergoes microtweening upon deformation.

According to another aspect, the present invention provides a system for providing welding for joining high manganese steel and low carbon steel, the system comprising:

carbon in the range of 0.1% to 0.4% by weight, manganese in the range of 15% to 25% by weight, chromium in the range of 2.0% to 8.0% by weight, molybdenum in an amount up to 2.0% by weight, nickel in an amount up to 10% by weight, 0.7 weight a consumable wire electrode producing a weldment comprising the remainder comprising silicon in an amount of % or less, sulfur in an amount of 200 ppm or less, phosphorus in an amount of 200 ppm or less, and iron; and

Gas metal arc welding power source for performing gas metal arc welding, generating a welding heat input of 2.5 kJ/mm or less

includes

In any aspect or embodiment described herein, the weldment comprises 0.1 to 0.3 weight percent carbon; 18.0 to 22.0 weight percent of manganese; 3.5 to 6.5% by weight of chromium; less than 1.5 weight percent molybdenum; 5.5 to 8.5 weight percent nickel; 0.4 to 0.8% by weight of silicon; less than 150 ppm sulfur; and/or 0.15 to 0.45 weight percent titanium in the preferred range.

In any aspect or embodiment described herein, the welding heat input is in the range of 0.6 to 1.0 kJ/mm.

According to a further aspect, the present invention provides a method for producing a weld deposit of erosion/corrosion resistant high Mn steel, said method comprising:

a high Mn steel base and a low carbon steel base to be welded, and

carbon in the range of 0.1% to 0.4% by weight, manganese in the range of 15% to 25% by weight, chromium in the range of 2.0% to 8.0% by weight, molybdenum in an amount up to 2.0% by weight, nickel in an amount up to 10% by weight, 0.7 weight Weld filler metal comprising the balance comprising silicon in an amount of % or less, sulfur in an amount of 100 ppm or less, phosphorus in an amount of 100 ppm or less, and iron.

providing; and

melting and cooling the weld filler material to produce a weld weldment;

includes

In any aspect or embodiment described herein, said melting comprises providing a weld heat input to the weld filler metal of 2.5 kJ/mm or less.

In any aspect or embodiment described herein, the at least two steel base metals comprise a portion to be welded, wherein the portion has a slope greater than 25°, and wherein the at least two metals comprise at least one high Mn steel and one It has more than low carbon steel.

In any aspect or embodiment described herein, the weld deposit has a yield strength in the welded state greater than the yield strength of the low carbon steel base metal and/or the high Mn steel base metal.

In any aspect or embodiment described herein, the weld deposit has a yield strength of greater than 60 ksi in the welded state; The weld deposit has an ultimate tensile strength greater than 70 ksi in the welded state.

In any aspect or embodiment described herein, the weld deposit has, at -29°C, a welded state CVN greater than 27 J; The heat affected zone of the base metal, at -29°C, has a post-weld CVN greater than 27J.

In any aspect or embodiment described herein, the high Mn base metal is an erosion/corrosion resistant high Mn steel.

While the present invention has been described in principle in the context of steel compositions for use primarily in oil, gas and/or components for petrochemical industry/systems/applications, such description has been used for the purpose of the present invention only and the present invention It is not intended to limit Conversely, it should be appreciated that the disclosed steel compositions may be used in a variety of applications, systems, operations, and/or industries.

While the systems and methods of the present invention have been described with reference to exemplary embodiments thereof, the present invention is not limited to such exemplary embodiments and/or implementations. Rather, the systems and methods of the present invention may be susceptible to many embodiments and applications, as will be readily apparent to those skilled in the art from the disclosure herein. The present invention expressly encompasses such modifications, improvements and/or variations of the disclosed embodiments. Since many changes can be made in the above construction, and many other embodiments of the invention can be made without departing from the scope of the invention, everything contained in the drawings and specification is to be construed as illustrative and not restrictive. should not be interpreted Further modifications, changes and substitutions are intended in the above disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims (17)

A welding composition for bonding a high manganese steel base metal to a low carbon steel base metal, the composition comprising:
carbon in the range of 0.1% to 0.4% by weight;
manganese in the range of 15% to 25% by weight;
2.0 wt% to 8.0 wt% chromium;
molybdenum in an amount up to 2.0% by weight;
nickel in an amount of up to 10% by weight;
silicon in an amount up to 0.7% by weight;
sulfur in amounts up to 100 ppm;
phosphorus in amounts of 200 ppm or less; and
balance containing iron
including,
wherein the weldment comprises an austenitic microstructure. The method of claim 1,
A composition further comprising titanium in an amount of up to 0.7% by weight. 3. The method of claim 2,
A composition comprising one or more of the following features:
0.1 to 0.3 weight percent carbon;
18.0 to 22.0 weight percent manganese;
chromium from 3.5 to 6.5% by weight;
molybdenum in an amount of less than 1.5% by weight;
5.5 to 8.5 weight percent nickel;
0.4 to 0.8 weight percent silicon;
sulfur in an amount less than 150 ppm;
A preferred range of titanium is 0.15 to 0.45 wt %; or
combinations of these. 4. The method according to any one of claims 1 to 3,
wherein the austenitic microstructure is converted to hard α′-martensite and undergoes microtwinning upon straining. carbon in the range of 0.1% to 0.4% by weight, manganese in the range of 15% to 25% by weight, chromium in the range of 2.0% to 8.0% by weight, molybdenum in an amount up to 2.0% by weight, nickel in an amount up to 10% by weight, 0.7 weight a consumable wire electrode producing a weldment comprising the remainder comprising silicon in an amount of % or less, sulfur in an amount of 200 ppm or less, phosphorus in an amount of 200 ppm or less, and iron; and
Gas metal arc welding power source for performing gas metal arc welding, generating a welding heat input of 2.5 kJ/mm or less
A system for providing welding for joining high manganese steel and low carbon steel, comprising: 6. The method of claim 5,
wherein the weldment comprises titanium in an amount of 0.7 wt % or less. 7. The method of claim 6,
The weldment comprises 0.1 to 0.3 wt% of carbon; 18.0 to 22.0 weight percent of manganese; 3.5 to 6.5% by weight of chromium; less than 1.5 weight percent molybdenum; 5.5 to 8.5 weight percent nickel; 0.4 to 0.8% by weight of silicon; less than 150 ppm sulfur; 0.15 to 0.45 weight percent titanium in the preferred range; or a combination thereof. 8. The method according to claim 6 or 7,
wherein the welding heat input is in the range of 0.6 to 1.0 kJ/mm. a high Mn steel base and a low carbon steel base to be welded, and
carbon in the range of 0.1% to 0.4% by weight, manganese in the range of 15% to 25% by weight, chromium in the range of 2.0% to 8.0% by weight, molybdenum in an amount up to 2.0% by weight, nickel in an amount up to 10% by weight, 0.7 weight Weld filler metal comprising the balance comprising silicon in an amount of % or less, sulfur in an amount of 100 ppm or less, phosphorus in an amount of 100 ppm or less, and iron.
providing; and
melting and cooling the weld filler material to form a weld deposit;
A method of producing a weld deposit of erosion/corrosion resistant high Mn steel comprising: 10. The method of claim 9,
wherein the melting comprises providing a weld heat input of no greater than 2.5 kJ/mm to the weld filler metal. 10. The method of claim 9,
wherein at least two steel base metals comprise a portion to be welded, wherein the portion has a bevel greater than 25°, and wherein the at least two metals have at least one high Mn steel and at least one low carbon steel. 12. The method according to any one of claims 9 to 11,
wherein the weld deposit has a yield strength in an as-welded state greater than a yield strength of the low carbon steel base metal and/or the high Mn steel base metal. 12. The method according to any one of claims 9 to 11,
A method comprising one or more of the following features:
wherein the weld deposit has a yield strength greater than 60 ksi in the welded state;
wherein the weld deposit has an ultimate tensile strength greater than 70 ksi in the welded state; or
combinations of these. 12. The method according to any one of claims 9 to 11,
A method comprising one or more of the following features:
the weld deposit, at -29°C, has a welded state CVN greater than 27J;
the heat affected zone of the base metal, at -29°C, has a post-weld CVN greater than 27J; or
combinations of these. 12. The method according to any one of claims 9 to 11,
wherein the high Mn base metal is erosion/corrosion resistant and high Mn toughness. The method of claim 1,
wherein the weld deposit produced by the welding composition has a yield strength greater than 60 ksi in the welded state. The method of claim 1,
wherein the weld deposit produced by the welding composition has an ultimate tensile strength of greater than 70 ksi in the welded state.

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